Exact Time Convergent Distributed Secondary Frequency and Voltage Control for AC Microgrid

This paper focuses on the exact time (ExT) convergent secondary voltage and frequency control for an autonomous AC microgrid (MG). The proposed approach ensures that the output states (i.e., voltage and frequency) of distributed generators (DGs) reach their desired value within a user-specified ExT. In addition to restoring the MG's states, the ExT controller economically distributes the active power demand among all DGs and proportionally allocates the reactive power demand. Moreover, a new distributed predefined-time sliding mode observer is developed to estimate the average voltage of all DGs within a user-defined time, set by a single observer parameter. The proposed observer exhibits significant improvements compared to finite-time and fixed-time observers. A rigorous convergence and robustness analysis, based on the Lyapunov stability theory, guarantees the ExT convergence of both tracking and consensus errors. Extensive simulation results validate the superiority of the proposed control method over state-of-the-art techniques.